This invention relates to a device for pneumatically supplying fiber flocks, e.g. cotton, synthetic fiber material, etc. to a chute or the like, wherein via a feed conduit, the fiber material is conveyed by means of transport air, comprising an air collecting chamber separated by an air-permeable vertical intermediate wall from the feeding chute connected with the transport channel, the air-collecting chamber being provided with a closable blow-off opening for discharging the flow of transport air, and a method for feeding fibers into textile machines by deflecting a mixture of fibers and transport air into a feeding chute, separating the transport air from the fiber material in a feeding chute equipped with an air-permeable intermediate wall, blowing off the transport air from an air collecting chamber arranged behind the air-permeable intermediate wall, and supplying the fiber material from the lower end of the feeding chute.
Such devices are used, for example, for carding machines in order to supply a rather uniform compacted mat of material to the machines. In doing so, the fibers are conveyed in pipelines in a mixture of fiber material and transport air and filled into the feeding chutes associated with the textile machines by deflecting the flow of transport air.
In supplying fiber material to a chute, it is important that the fiber material is uniformly distributed over the width of the chute when it is discharged from the pneumatic feed line and that the fiber material in the feeding chute is uniformly piled over the width and depth thereof. In general, transport air of the pneumatic feed is discharged at one wall surface of the feeding chute. To this effect, one longitudinal wall of the feeding chute is either permeable or it contains corresponding apertures. However, it may happen that fiber material more or less adheres to the air-permeable wall through which transport air shall get out, so that the release of the transport air is impaired with a resultant disadvantageous effect for the filling density of the feed chute. The way in which the dropped fiber flocks are distributed in the feeding chute is merely accidental. If the fiber material caught by the perforated wall of the feeding chute and having a more or less long residence time at the screen surface during the evacuation of transport air exceeds a specific weight of mass, it drops by overweight from the screen surface. However, such events are irregular and beyond control. The piling of fibers in the chute is substantially accidental.
According to German Patent 33 15 909, it has been known for a device, producing a mat of fiber flocks comprising a substantially vertical chute of a continuous rectangular cross section in the upper part of which ends a feed line for fiber flocks, while the lower chute end includes a means extending over its width for extracting the fibers as a mat, that a plurality of scanning points distributed over the width of the fiber mat is provided for detecting the mat density. Said measuring points are connected via a control means and a corresponding number of elements provided at various points of the chute for changing the air flow prevailing at said points in the chute. The measuring points may be pedal troughs. Such an arrangement is very involved. Air flow is influenced subsequently, i.e. after the mat has left the feed means over a considerable path length.
In a known feeding device for fiber material (European Patent 0 176 668), a feeding chute is disposed below the pipeline, which is separated from an air-collecting chamber by an air-permeable intermediate wall. The air-permeable wall has its upper end provided with an opening through which the transport air, separated from the fiber material at the intermediate wall, may be supplied to a waste air line. The section of the passage of the opening can be varied by means of a pivotable flap. A pair of rolls is arranged at the end of the feeding chute for feeding the fiber material from the feeding chute to the successive machine.
In doing so, the opening at the upper end of the air-collecting chamber, which is variable in the degree of opening and which can also be shut off, serves for regulating the supply of fiber material from the pipe to the feeding chute by the rate of the transport air discharged. In the extreme case, i.e. with the opening shut, no fiber material can fall into the feeding chute, at least in theory, since the flow of transport air is not deflected into the feeding chute because of the pressure-tight closure of the air-collecting chamber and the feeding chute. In such a feeding chute arrangement, there is no vibration of the fiber material contained in the feeding chute, so that there is no levelling of the height of the stack of fiber material over the width of the feeding chute, and, therefore, the weight load and the unit pressure on the lowest fiber layer in the feeding chute differ, which results in a non-uniformly compacted fiber mat being supplied to the successive machine.
It is the object of the invention to provide a device of the initially mentioned type wherein a maximum levelling of the fiber material over the width of the device is achieved.
It is a further object of the invention to design and configure a feeding chute having a permeable wall surface for discharging transport air in such a way that, without a positively operating control means, the fiber material is piled directly in a substantially uniform density over the width of the chute.